Bag and method of making the same

ABSTRACT

A bag suitable for use in microwave cooking is constructed of an elongated tube of flexible material closed at one end by means of a cold seal closure and having a heat seal adhesive deposit applied to the other end thereof for use in closing the bag after filling thereof; and methods of making the same are described, including the making of a roll from which said bags can be made.

This application is a continuation-in-part of application Ser. No.08/278,919 filed Jul. 22, 1994, which has been allowed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a bag of the type usable in microwave cookingof food products, such as popcorn. The invention also relates to amethod of making a bag of the indicated type.

2. Description of the Prior Art

Microwave popcorn bags are well known. Illustrative of bags of this typeare those disclosed in U.S. Pat. Nos. 3,691,374; 3,851,574; 3,973,045;4,461,031; 4,571,337; 4,691,374; 4,892,744; and 5,044,777.

Although bags of the above-indicated type are generally satisfactory,there is need for improvement thereof in two areas, namely, in the costof manufacture, and in the use of microwave packages made therefrom.Present day bags of the indicated type are formed into packagescontaining popcorn kernels, the packages being closed at upper and lowerends thereof by means of heat seals formed by the application of heatand pressure. The use of heat seals to close both ends of the bag is thesource of two problems. The first problem is that it is difficult toprovide a bag making process which can operate at a high speed becausethe formation of a heat seal closure requires a considerable dwell time,which extends the length of the production line. Another problem is thatheat seal closures are difficult to open after the microwave cookingoperation in order to gain access to the cooked product.

Attempts to provide an easily openable popcorn package are disclosed inU.S. Pat. No. 4,571,337, which illustrates in FIGS. 7 and 8 the mannerin which the bag is opened by pulling on diagonally opposite corners atthe upper end of a package after the microwave cooking operation iscompleted. The use of a heat seal closure as disclosed in U.S. Pat. No.4,571,337, which is illustrative of the prior art, has proved to presentproblems in the easy opening of the bag. In many applications with theheat sealed closures of the prior art, the closure strength provided bythe heat seal is greater than the tear strength of the paper forming theside panels of the bag thereby resulting in torn bags, spilled popcorn,and possible steam exposure to the consumer during the opening of thebag.

SUMMARY OF THE INVENTION

It is the general object of the present invention to provide a bagsuitable for use in microwave cooking which comprises an elongated tubeof flexible material sealed at one end by a cold seal closure andadapted to be sealed at its other end by a heat seal closure.

By reason of the construction in accordance with the invention whereinthe bag is made with a cold seal at one end, it is possible to provide ahigh speed, compact bag making process which does not require theformation of a heat seal during the making of the bag.

In accordance with another feature of the invention, the cold sealclosure can be designed to respond to the microwave cooking operation soas to provide a peelable closure which can be opened without tearing theside panels of the bag structure. Moreover, the openability of the coldseal closure is maintained for a longer time period after a cookingoperation since it functions at lower temperatures than a comparableheat seal closure.

Another object of the invention is to provide methods of making a bag ofthe indicated type including the making of a roll comprising a tubularweb from which a plurality of said bags can be made.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a microwave popcorn bag pursuant to afirst embodiment of the invention.

FIG. 2 is a sectional view taken on line 2--2 of FIG. 1.

FIG. 3 is a sectional view taken on line 3--3 of FIG. 1.

FIG. 4 is a detail view showing the cold seal of the bag shown in FIG.1.

FIG. 5 is a perspective view of a microwave popcorn bag pursuant to asecond embodiment of the invention.

FIG. 6 is a sectional view taken on line 6--6 of FIG. 5.

FIG. 7 is a sectional view taken on line 7--7 of FIG. 5.

FIG. 8 is a detail view showing the cold seal of the bag shown in FIG.5.

FIG. 9 is a perspective view showing a package in accordance with theinvention.

FIG. 10 is a view showing a first step in the procedure for providing apackage made of the bag in accordance with the invention.

FIG. 11 is a view showing a second step in the method of making thepackage in accordance with the invention illustrating the step of heatsealing the top of the bag to close the same.

FIG. 12 is a view illustrating the procedure used to manually open theheat sealed end of the package after a microwave cooking operation inorder to gain access to the contents of the package.

FIG. 13 is a side elevation, partly in diagrammatic form, showing amanufacturing process line for making a bag in accordance with theinvention.

FIG. 14 is a plan view of a part of a web for use in forming the bag inaccordance with the invention.

FIG. 15 is a detail view showing part of one work station of the processline shown in FIG. 13.

FIG. 16 is a view showing a tube formed during the process of making abag in accordance with the invention.

FIG. 17 is a detail view of the mechanism for forming the cold seal atone end of the bag in accordance with the invention.

FIG. 18 is a side elevation, partly in diagrammatic form, showing amanufacturing process line for making a tubular roll from which bags inaccordance with the invention can be made.

FIG. 19 is a detail view of the mechanism employed in the process lineshown in FIG. 18 for forming the cold seal at one end of the bag inaccordance with the invention.

FIG. 20 is a sectional view taken on line 20--20 of FIG. 19.

FIG. 21 is a side elevation, partly in diagrammatic form, showinganother manufacturing process line for making a tubular roll from whichbags in accordance with the invention can be made.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIGS. 1 to 4, there is shown a bag 10 in accordance with theinvention suitable for use as a microwave popcorn bag. Bag 10 has aconventional pinch bottom bag construction comprising a tubularconstruction including a pair of opposed rectangular side panels 11 and13 joined by a pair of opposed inwardly-folded gusseted side panels 12and 14, all of which extend between and define an open end 16 and asealed closed end 18 of the tubular construction shown. Bag 10 is madeof a single-ply of flexible material, such as, for example, agrease-resistant paper of approximately 25-35 pounds per ream of a typewell known in the art.

The tube forming the bag 10 is sealed along a longitudinal seam 19 bymeans of an aqueous adhesive as is conventional in the art.

The closed end 18 is sealed by a cold seal closure 20 in accordance withthe invention. The term "cold seal" (also referred to in the art as a"cohesive seal") is used in the art, and hereinafter, to define a sealor bond formed by an adhesive which exhibits an affinity for itself,whereby when two separate surfaces having said adhesive thereon arebrought together under pressure, they exhibit a strong tendency to stickto each other. The "cold seal" or "cohesive seal" in accordance with theinvention is formed by an adhesive which provides a "fiber tearing" or"destruct" bond on the paper material, without the aid of heat or dwelltime (as is required in a typical heat seal), when brought togetherunder pressure only. The adhesive deposited to produce the cold sealclosure 20 is a cohesive with good adhesion to paper substrates andhaving heat resistance in a microwave application, an example of whichis a cold seal cohesive available from VALLEY ADHESIVES and COATINGCORPORATION of Appleton, Wis. and sold under the tradename "Instabond"and designated as product C-2179-A. More specifically, this cohesive isa natural latex cohesive having a density of approximately 8.3 lbs/gal.

By way of example, the cold seal adhesive is applied in a patterncomprising a three-quarter inch wide band extending around the innersurface of panels 11-14 at the end 18 of the bag 10 shown in FIG. 1 at adry coating weight of two to four pounds per ream, with bag 10 being 6.0inches wide and 11.625 inches long.

The cold seal closure 20 is constructed and arranged to provide a bondwhich at ambient temperature cannot be opened without tearing the papermaterial, but which at an elevated temperature, such as that produced onthe closure 20 by a microwave cooking operation, will be softened toform a "peelable" closure that can be opened easily without tearing thepaper material by the manual application of a separating force whichpulls side panels 11-14 apart. The term "peelable" as used in the art,and herein, is defined as the property whereby two plies of adheredmaterial can be separated with failure occurring in the adhesive and notin the surface of the plies. Thus, cold seal closure 20 is made towithstand the rigors of microwave cooking and provide the "easy open"operation described above.

At the open end 16 of bag 10, there is provided a deposit of a heat sealadhesive 22 for use in closing this end of the bag 10 after the bag 10is filled with popcorn kernels, and oil usually, by the packager. Theheat seal adhesive 22 is applied in a pattern comprising a bandextending around the inner surface of the panels 11 to 14. In theexample of a 6×11.625 inch bag described above, the band of heat sealadhesive 22 has a width of approximately 1.375 inches. The applicationand arrangement of heat seal adhesive 22 is pursuant to present daypractice. In accordance with the invention, the deposit of heat sealadhesive 22 is adapted to form a heat seal closure that forms a bondthat is stronger (i.e., can better withstand the force therein caused byexpanded gases produced within the bag 20 during cooking) than the bondformed by cold seal closure 20 at the elevated temperatures produced bya microwave cooking operation for which bag 10 is made. Moreover, thecold seal closure in accordance with the invention is particularlysuited to being constructed and arranged to provide controlled ventingwhereby the package is vented at the end having the cold seal closure ata desired stage of the microwave cooking. This obviates a problem withthe prior art packages having heat seal closures at both ends whereinthe desired venting fails to occur thereby resulting in a poorly cookedproduct.

Side panel 11 is provided with a susceptor 24 formed of apaper/metalized polyester film laminate. It will be apparent that a widevariety of metals and polyester films can be used to produce susceptor24. Susceptors are well known in the art and, generally, the preferredpolyester film is PET (polyethylene terephthalate) and the metal ispreferably aluminum. Susceptor 24 is a rectangular patch attached to thematerial forming bag 10 during the bag making process. Instead ofproviding a patch, it is also known in the art to print a susceptormaterial on the paper layer or on another laminating material.

The microwave popcorn bag 10 shown in FIGS. 1 and 2 is very economicalto manufacture and can be formed into a popcorn package which is veryeasy and effective to use. Thus, bag 10 is closed at its one end 18 bythe cold seal closure 20 described above and is open at its other end 16which is used for filling the enclosed space within bag 10 locatedbetween the side panels 11-14. After filling the bag 10 with the desiredamount of popcorn kernels, the end 16 is sealed in a conventional heatsealing procedure by applying heat and pressure to this end of the bag10 to provide a heat sealed closure along the band of adhesive 22 as isconventional in the art. It is also common practice to tack the gussetedpanels 12 and 14 together at end 16 by the use of heat seal adhesiveapplied to the opposing exterior surfaces thereof as is conventional inthe art.

The bag 10 is also easy to use because the cold seal closure 20 isdesigned to form a peelable closure that, upon the application theretoof heat from a microwave cooking operation, can be opened easily withouttearing by the manual application of a separating force which pulls theside panels 11-14 apart. This opening procedure is conventional in theart and is disclosed in the above-discussed patents. However, the novelcold seal closure 20 in accordance with the invention provides betterresults and permits the use of lighter weight microwavable bagstructures, such as the single ply material for bag 10.

In FIGS. 5 to 8, there is shown a microwave popcorn bag 10' which isessentially the same as the bag 10 shown in FIGS. 1 to 4, wherefore,corresponding parts are given the same reference numerals with primesadded.

Bag 10' is the same size as bag 10 and also suitable for use as amicrowave popcorn bag. Bag 10' has a conventional pinch bottom bagconstruction comprising a tubular construction including a pair ofopposed rectangular side panels 11' and 13' joined by a pair of opposedinwardly-folded gusseted side panels 12' and 14', all of which extendbetween and define an open end 16' and a sealed closed end 18' of thetubular construction shown. Bag 10' is made of a two-ply flexiblematerial, such as, for example, an inner ply of grease-proof paper ofapproximately 20-25 pounds per ream and outer ply of bleached or naturalkraft paper of approximately 20-25 pounds per ream, said two-plymaterial being well known in the art.

The tube forming the bag 10' is sealed along a longitudinal seam 19' bymeans of an aqueous adhesive seal as is conventional in the art. Theclosed end 18' is sealed by a cold seal closure 20' such as cold seal 20described above except that cold seal 20' is applied to the innersurface of the inner ply of the two-ply material used to make bag 10'.

At the open end 16' of bag 10', there is provided a deposit of a heatseal adhesive 22' for use in closing this end of the bag after the bag10' is filled with popcorn kernels. The heat seal adhesive 22' islocated at a band extending around the inner surface of the inner ply ofthe panels 11' to 14' and is the same as heat seal adhesive 22 describedabove.

Side panel 11' is provided with a susceptor 24' formed of a metalizedpolyester film as is conventional in the art. It will be apparent that awide variety of metals and polyester films can be used to producesusceptor 24'. Susceptors are well known in the art and generally thepreferred polyester film in PET (polyethylene terephthalate) and themetal is preferably aluminum. Susceptor 24' is a rectangular patchlocated on side panel 11' between the plies of the material forming bag10' and is inserted in position during the bag making process as isconventional in the art.

The microwave popcorn bag 10' shown in FIGS. 5 to 8 is very economicalto manufacture and can be formed into a popcorn package which is veryeasy and effective to use. Thus, bag 10' is closed at its one end 18' bythe cold seal closure 20' described above and is open at its other end16' for use in filling the enclosed space within bag 10' located betweenthe side panels 11'-14'. After filling the bag 10' with popcorn kernelsand oil, the end 16' is sealed in a conventional heat sealing procedureby applying heat and pressure to this end of the bag 10' to provide aheat sealed closure as is conventional in the art.

The bag 10' is also easy to use because the cold seal closure 20' isdesigned to form a peelable closure that, upon the application theretoof heat from a microwave cooking operation, can be opened easily withouttearing by the manual application of a separating force which pulls theside panels 11'-14' apart as is conventional in the art and as isdisclosed in the above-discussed patents.

FIG. 9 shows a microwave popcorn package 100 manufactured from a bag 10in accordance with the invention. The bags 10 are shipped to a packagerwho completes the making of the package. Package 100 contains a quantityof unpopped kernels of corn 102 and has the end 16 of bag 10 sealed by aconventional heat seal closure 106. The filling of the bag 10 with aquantity of corn kernels is done through the open end 16 as shown inFIG. 10 after which this end 16 is closed by conventional heat sealingprocedure illustrated in FIG. 11. As shown in FIG. 11, a pair of sealingjaws 108, at least one of which is heated, are pressed together acrossthe upper ends of side panels 11 and 13 in the area of the heat sealadhesive deposit 22. As the jaws 108 are pressed together for a setdwell time under conditions of heat and pressure, a desired heat sealclosure 106 is formed at the end 16 of bag 10.

FIG. 12 illustrates the procedure for opening a package 100 after thecompletion of a microwave cooking operation. It will be apparent thatduring the microwave cooking operation, the contents of the package 100,as well as the sealed closures 20 and 106, are heated, and the increasedpressure of the gases within the package 100 cause it to expand acertain amount due to the generation of water vapor from the poppingcorn kernels. This applies pressure to the sealed closures 20 and 106,which, if desired can be designed to provide for venting as is wellknown in the art. The cold seal closure 20 is particularly suitable forthe design of controlled venting as desired.

After the microwave cooking operation is completed, the popped corn isremoved from the package 100 by manually opening the end 18 of the bagas illustrated in FIG. 12. The consumer is instructed on the package 100to open the bag 10 carefully by pulling on top diagonal corners whileavoiding contact with escaping steam. As discussed above, the novel coldseal closure 20 in accordance with the invention is constructed andarranged to provide a peelable closure when the bag 10 has itstemperature elevated as a result of the microwave cooking operation forwhich it is made. What occurs is that the cold seal closure 20 becomessoftened when exposed to the heat produced to thereby form a peelableclosure that can be opened easily, without tearing the paper materialproviding the side panels 11-14, by the manual application of aseparating force (as illustrated in FIG. 12) which pulls side panels11-14 apart. It will be noted that the heat seal closure 106 isconstructed and arranged so that it requires a higher separating forceto open the same than the force required to open the cold seal closure20 during and on completion of the microwave cooking operation.Moreover, as discussed above, the cold seal closure 20 can readilyprovide controlled venting and obviate the problems of non-venting thatcan occur in packages with heat seal closures at both ends.

A method of making a bag in accordance with the invention is shown inFIGS. 13 to 17. An initial step in the method is to provide a web 30 offlexible material for use in forming a tube, said web of material havinga plurality of successive web lengths 32 of equal size such as thatshown in FIG. 14 wherein part of a flat web 30 is illustrated. Each weblength 32 has a first deposit 20A of a cold seal adhesive suitable forforming the cold seal closure 20 at its one end and a second deposit 22of a heat seal adhesive suitable for forming the heat seal closure 106of package 100 (as described above) at its other end. Deposits 20A and22 extend transversely across each web length 32 at the ends thereof asshown in FIG. 14. Each web length 32 extends between the twotransversely extending cut-off lines indicated at 34 in FIG. 14 andlocated adjacent to and outwardly of adhesive deposits 20A and 22. Inorder to make a bag 10 of the 6.0×11.625 inch size described above, eachweb length 32 is 21.0 inches wide and 11.625 inches long.

After web 30 has adhesive deposits 20A and 22 applied thereto (which istypically done by a printing operation), it is wound into a large coiland delivered to the bag making machine. In the case of bag 10, theadhesive deposits are applied to a web used to provide the single ply ofmaterial from which bag 10 is made. In the case of bag 10', the adhesivedeposits are applied to a web used to provide the inner ply of thetwo-ply material from which bag 10' is made.

In FIG. 13, there is shown a production line for making a pinch bottombag such as the bag 10' shown in FIGS. 5 to 8. In FIG. 13, arrows areused to show the direction of movement of the webs through the bagmaking machine shown therein. At its input end at the right end of FIG.13, there is provided a flexographic printing press 40 which has theouter ply of the two-ply bag material fed therethrough from a coil 41thereof (as shown by the arrows in FIG. 13) so that the desired inkprinting is applied on the side of the outer ply which will be formedinto the outer surface of the bag 10'. This printing press arrangementis conventional in the art.

The outer ply is fed from the press 40 across idler rollers 42 and 44 toa work station 46 whereat the susceptor patch is applied to the innersurface outer ply from a coil 48' thereof by a construction that isconventional in the art. The outer ply with the susceptor patch appliedthereto is then passed through a work station 48 whereat the liner, orinner ply of the two-ply bag material, is laminated onto the inner sideof the outer ply by an arrangement conventional in the art. Also at workstation 48, the seam adhesive for forming the longitudinal seam 19 isapplied by a glue applicating roller indicated at 49. The liner issupplied from a pre-printed coil 50' which has the cold seal adhesivedeposit 20A and heat seal adhesive deposit 22 pre-applied thereto in thearrangement of web lengths 32 as shown in FIG. 14.

The two-ply web with the seam adhesive thereon and the susceptor patcheslocated between the plies is then fed from the work station 48 to a tubeforming machine 50. The tube forming machine 50 is conventional and isconstructed and arranged for the forming of a tube from a flat web bymeans of a conventional former plate arrangement. Because of thetackiness of the cold seal adhesive deposit 20A, a "Teflon" former isused, which reduces friction between the adhesive and the former plate.The conventional forming machine 50 operates by forming a tube aroundformer plates and then passing a formed tube-shaped web between a pairof cooperating draw rollers 52 and 54 (FIG. 15) to a pair of cut-offrollers 56 and 58 which cut this web along the transverse cut-off lines34 to form tube lengths 59 as shown in FIG. 16.

From the cut-off rollers 56 and 58, a formed and cut-off tube length 59is fed by a pair of transfer rolls 60 and 62 to a work station 64 shownin FIG. 17 whereat the cold seal closure 20 is formed. As shown in FIG.15, the tube length 59 passes from the cut-off rollers 56 and 58 and isfed by a pair of transfer rollers 60 and 62 between a pair of rollers 66and 68 which form the cold seal closure 20 at the end of the tube length59 by an arrangement shown in detail in FIG. 17. To this end, the lowerroller 68 is made of a high durometer rubber and the upper rollercomprises a crimp block 67, which is a metal strip extending across theentire width of the tube length and mounted in a recess on the peripheryof roller 66. Crimp block 67 has the desired crimp pattern, namely, aplurality of rib-like projections, formed in its outer surface facinglower roller 68. The position of the rollers 66 and 68 are controlled byan air regulated system to ensure that a consistent pressure (such asproduced by a pressure setting of 50-90 PSI) is applied to the end ofthe tube length 59 passing therebetween so to pressurize the same inorder to form the cold seal closure 20 in accordance with the invention.

The completed bag 10', which comprises a tube with the cold seal closure20 formed at its one end, is then fed around a drum 80 and stored in acollector area 82 for pick-up.

The production line shown in FIG. 13 is essentially conventional exceptfor the portion thereof whereat the formed tube 59 is fed to the coldsealing station 64. As is apparent from the consideration of thedrawings, the production line is very compact and is arranged in astraight line whereby it can be constructed to operate at very highspeeds. In prior comparable pinch bottom production lines, the length ofthe line required to produce the conventional heat seal closure at oneend of the pinch bottom bag is much longer than that of the cold sealstation 64 shown in FIG. 13 and requires a considerable dwell time toperform the heat seal closure step.

A method of making a bag 10 as shown in FIGS. 1 to 4 is essentially thesame as that shown in FIGS. 13 to 17, the only difference being that asingle ply of material is used and there is no need to combine two pliesas described in the method described above. In this case, a coil of thesingle ply material is mounted in the press 40 at the same location asthe coil 41 for the outer ply and a liner coil 50' is not necessary.

In FIG. 18, there is shown a production line for making a continuoustubular web comprised of a plurality of tube lengths which can be madeinto a pinch bottom bag 10, said web being wound into a roll from whicha plurality of said bags 10 can be cut in a subsequent package formingoperation wherein a package such as that shown hereinbefore can be made.

The production line shown in FIG. 18 comprises an unwind station 110which includes a roll 111 of a single ply material of the type describedabove for making the bag 10, said roll 111 being mounted on a spool 112with the web being fed from the roll 111 around a pair of dancer rollers113 which feed the web around a roller 114 at the entry end of aprinting station 120 comprising three pairs of rollers 122, 123, and124. The pairs of rollers 122 and 123 are constructed and arranged toprint onto the web passing therethrough the strips of the adhesivedeposits 20A and 22, respectively, which are arranged as shown in FIG.14. Thus, as the web is fed upwardly from the rollers 124 to leave theprinting station 120, the web is in the condition such as that shown inFIG. 14 wherein part of a flat web 30 is illustrated. Thus, each weblength 32 has a first deposit 20A of a cold seal adhesive suitable forforming the cold seal closure 20 at its one end and a second deposit 22of a heat seal adhesive suitable for forming the heat seal closure, suchas the heat seal closure 106 of package 100 (as described above), at itsother end. Deposits 20A and 22 extend transversely across each weblength 32 at the ends thereof with each web length 32 extending betweentwo transversely extending spaced apart cut-off lines indicated at 34and located adjacent to and outwardly of adhesive deposits 20A and 22 asis shown in FIG. 14.

From printing station 120, the web moves upwardly into a drying tunnel125, and passes around a roller 126 and back downwardly to an exitroller 128 at the lower end of the drying tunnel 125. As the web travelsthrough the drying tunnel 125, heat is applied thereto to dry theadhesive deposits 20A and 22 applied at the printing station 120.

The web is fed from the roller 128 of drying tunnel 125 downwardly intoa second printing station 130 which applies the graphics to the websurface which is to become the outer surface of the formed bag. Theprinting station 130 shown in FIG. 18 comprises four pairs of printingrollers 136, 137, 138, and 139, three of which are used for theapplication of colors to produce the desired graphics and one of whichis used for the application of a heat seal adhesive for tacking thegusseted panels together at the heat seal end of the bag.

From the second printing station 130, the web is fed to a second dryingtunnel 140 and passes sequentially around lower roller 141, upper roller142, and lower roller 143. As the web is passed through the seconddrying tunnel 140, heat is applied thereto to dry the ink providing thecolors printed thereon and the heat seal adhesive for the gussets.

From the second drying tunnel 140, the web is fed to a patching station146 which is essentially the same as patching station 46 described abovewith respect to the production line shown in FIG. 13. At the patchingstation 146, a susceptor patch is applied to the inner surface of theweb and the web with the susceptor patch applied thereto is fed to aroller 149 at the inlet of a tube forming machine 150 which isessentially the same as the forming machine 50 described above withrespect to the production line shown in FIG. 13. At the entry roller149, the seam adhesive for forming the longitudinal seam 19 is appliedby a glue applicating roller. From this roller 149, the web is fed intothe tube forming machine 150 which forms a continuous tube from a flatweb by means of a conventional former plate arrangement. Forming machine150 forms a tube around former plates and then passes the tube-shapedweb between a pair of rollers 152 and 154 to the next work stationindicated at 64'.

As shown in FIGS. 19 and 20, the tube formed by the forming machine 150comprises a pair of opposed flat sides, such as sides 11 and 13 of thebag 10, and a pair of opposed intucked sides, such as the sides 12 and14 of the bag 10.

From this point whereat the tubular web is fed from the former 150, theproduction line shown in FIG. 18 differs from that shown in FIG. 13 inthat the tubular web is not cut into a plurality of separated tubelengths, but, instead, is fed directly to the work station 64'comprising the pair of rollers 66 and 68 as shown in FIG. 17 anddescribed in detail above. Thus, rollers 66 and 68 are operable to formthe cold seal closure 20 at the end of the successive continuous tubelengths indicated at 59' in FIG. 19. The station shown at 64' is shownin detail in FIG. 19 and comprises a lower roller 68 made of a highdurometer rubber and an upper roller 66 comprising a crimp block 67,rollers 68 and 66 being described in detail above with respect to FIG.17. The work station 64' is essentially the same as work station 64shown in FIG. 17, the only difference being that the web passing betweenthe rollers 66 and 68 is a continuous tubular web comprising successivetube lengths 59' and has not been cut into a plurality of separated tubelengths 59 as is the case in the method shown in FIG. 13.

After the cold seal closure 20 is formed at station 64', the continuoustubular web is passed around a pair of entry rollers 172 of a rewindstation 170. From the two entry rollers 172, the tubular web is fedaround an idler roller 173 and wound onto a spool 174 into a roll 180.It will be apparent that the roll 180 comprises a continuous tubular webwound into a rolled configuration and comprising a plurality ofsuccessive tube lengths 59' from which a plurality of bags 10 can bemade by simply cutting off the web along the cut-off lines 34 betweenthe locations whereat the heat seal and cold seal adhesives 22 and 20A,respectively, are applied.

The roll 180 formed by the production line shown in FIG. 18 can beremoved from the rewind station 170 and shipped to the packager whereatit can be placed in a package filling production line whereat the tubelengths 59' are cut into bags 10 as they are fed from the roll 180,whereupon the bags 10 can be filled and closed at the heat seal end toprovide a package such as that shown and described above.

In FIG. 21, there is shown a production line for making a continuoustubular web comprised of a plurality of tube lengths which can be madeinto a pinch bottom bag 10', said web being wound into a roll 96 fromwhich a plurality of said bags 10 can be cut in a subsequent packageforming operation wherein a package such as that shown hereinbefore canbe made.

The production line shown in FIG. 21 is similar to that shown in FIG. 13and comprises the same conventional flexographic printing press 40, thesame work stations 46 and 48, and the same conventional tube formingmachine 50. Thus, press 40 has the outer ply of the two-ply bag materialfor making bag 10' fed therethrough from a coil 41 thereof with thedesired ink printing applied to the side of the outer ply which will beformed into the outer surface of the bag 10'. The outer ply is fed fromthe press 40 across idler rollers 42 and 44 to work station 46 whereatthe susceptor patch is applied to the inner surface of outer ply from acoil 48' thereof. Also, at work station 48, the seam adhesive forforming the longitudinal seam 19' is applied by a glue applicatingroller indicated at 49 and the liner for the bag 10' is applied from apre-printed coil 50', which liner has the cold seal adhesive deposit 20Aand the heat seal deposit 22 pre-applied thereto in the arrangement ofthe web lengths 32 as shown in FIG. 14. The two-ply web with the seamadhesive thereon and the susceptor patches located between the plies atspaced apart intervals is then fed from the work station 48 to the tubeforming machine 50 which forms a continuous tube from a flat web bymeans of a conventional former plate arrangement. Forming machine 50forms a tube around former plates and then passes the formed tube-shapedweb between a pair of cooperating draw rollers 52 and 54 to the nextwork station indicated at 64'.

From this point whereat the tubular web is fed from the former 50, theproduction line shown in FIG. 21 differs from that shown in FIG. 13. Inthe production line shown in FIG. 21, the tubular web is not cut into aplurality of separated tube lengths but, instead, is fed directly to thework station 64' comprising of the pair of rollers 66 and 68 shown inFIG. 17 and described in detail above, said rollers 66 and 68 beingoperable to form the cold seal closure 20 at the end of each ofsuccessive tube lengths such as indicated at 59' in FIG. 19.

The station shown at 64' is shown in detail in FIG. 19 and comprises alower roller 68 made of a high durometer rubber and an upper rollercomprising a crimp block 67 identical to that described above withrespect to FIG. 17. The work station 64' is essentially the same as thatshown in FIG. 17, the only differences being that the tubular webpassing between the rollers 66 and 68 is a continuous tubular webcomprising successive tube lengths 59' and has not been cut into aplurality of separated tube lengths 59 as is the case in the methodshown in FIG. 13. As discussed above with respect to the arrangementshown in FIG. 17, the position of the rollers 66 and 68 are controlledby an air regulated system to ensure that a consistent pressure isapplied to the end of the tube length 59' passing therebetween so as topressurize the same in order to form the cold seal closure 20 inaccordance with the invention.

After the cold seal closure 20 is formed at station 64', the continuoustubular web is fed to a rewind station 70 whereat the tubular web is fedto a pair of entry rollers 72 and a roller 73 and wound onto a spool 74into a roll 96. It will be apparent that the roll 96 comprises acontinuous tubular web wound into a roll configuration, said roll 96comprising a plurality of tube lengths 59' from which a plurality ofbags 10' can be made by simply cutting off the tubular web along thecut-off lines 34 between the locations whereat the heat seal and coldseal adhesive 20A and 22, respectively, are applied.

The roll 96 can be shipped to the packager whereat it can be placed in apackage filling production line whereat the tube lengths 59' are cutinto bags 10' as they are fed from the roll 96 whereupon the bags 10'can be filled and closed at the heat seal end to provide a package suchas that shown and described above.

It will be apparent that the production line shown in FIG. 21 can bemodified easily to provide a production line for making a rollcomprising a continuous tubular web lengths which can be made into apinch bottom bag 10, the only difference being that a single ply ofmaterial is used and there is no need to combine two plies as describedin the method shown in FIG. 21. Also, in this case, a coil of the singleply material is mounted in the press 40 at the same location as the coil41 for the outer ply and a liner coil 50' is not necessary.

The main advantage of forming a roll such as the rolls 96 and 180comprising a continuous web having a plurality of the tube lengths asdiscussed above is that it eliminates individual bag handling at boththe bag making plant and at the plant where the bag is filled to form apackage.

While the invention has been disclosed by reference to the details ofpreferred embodiments, this disclosure is intended in an illustrativerather than in a limiting sense, as it is contemplated thatmodifications will readily occur to those skilled in the art, within thespirit of the invention and the scope of the appended claims.

What is claimed is:
 1. A roll comprising a continuous tubular web havinga plurality of tube lengths which can be made into bags suitable for usein microwave cooking,said tubular web comprising a flexible material,the flexible material including paper material, said tubular webcomprising a plurality of successive tube lengths connected serially inend-to-end relationship, each tube length comprising a plurality of sidepanels and having an open end and a closed end, a deposit of a cold sealadhesive across the inside of the closed end of each tube length forsealing the side panels together at the closed end of each tube length,said cold seal adhesive being an adhesive which exhibits an affinity foritself whereby when two separate surfaces having said cold seal adhesivethereon are brought together under pressure they exhibit a strongtendency to stick to each other which provides a tearing or destructbond on the flexible material without the aid of heat or dwell time, asis required in a typical heat seal, when brought together under pressureonly, said side panels of each tube length having pressure appliedthereto at locations whereat said cold seal deposit is located to form acold seal closure extending thereacross whereby each tube length isclosed at one end by said cold seal closure, said cold seal closureformed from the cold seal adhesive being such that at ambienttemperatures said cold seal closure cannot be opened without tearing theflexible material of the web and such that at elevated temperaturesproduced in microwave cooking said cold seal closure forms a peelableclosure that may be opened without tearing the flexible material of theweb, a deposit of heat seal adhesive at the open end of each tube lengthfor use in closing this end of the tube length after it is filled with aproduct, said heat seal adhesive deposit being in the form of a bandextending around the inner surface of the side panels at the open end ofeach tube length, and the deposit of heat seal adhesive being adapted toform a heat seal closure that forms a bond that is stronger than thebond formed by the cold seal adhesive at the elevated temperaturesproduced by microwave cooking operation.
 2. A roll according to claim 1including a susceptor patch attached to one of said side panels.
 3. Aroll according to claim 1 wherein said cold seal adhesive comprises anatural latex cohesive.
 4. A roll of microwave cooking bags comprisingacontinuous tubular web having a plurality of successive microwavecooking bags connected together serially in end-to-end relationship andseparated by cut-off lines, said bags being of pinch bottom bagconstruction including a pair of opposed rectangular side panels joinedby a pair of opposed inwardly-folded gusseted side panels, saidrectangular side panels having a middle portion and two side portions,said bags having an open end and a closed end, said bags being made ofgrease-resistant paper material, a cold adhesive sealing band across theinside of the closed end of the bag which seals the gusseted side panelsto the side portions of said opposed rectangular side panels so that thesealed gusseted side panels form flaps, and which seals the middleportion of said opposed rectangular side panels together, said bagshaving a longitudinal seam, said longitudinal seam being sealed by anaqueous adhesive, said cold adhesive being an adhesive which exhibits anaffinity for itself whereby when two separate surfaces having said coldadhesive thereon are brought together under pressure they exhibit astrong tendency to stick to each other which provides a fiber tearing ordestruct bond on the paper material without the aid of heat or dwelltime, as is required in a typical heat seal, when brought together underpressure only, said cold seal band providing a bond which at ambienttemperature cannot be opened without tearing the paper material, butwhich at elevated temperature, such as that produced by a microwavecooking operation, is softened to form a peelable closure bond that isopened easily without tearing the paper material by manually applying aseparating force which pulls the panels apart, a deposit of heat sealadhesive at the open end of the bags for use in closing this end of thebag after the bag is filled with a food product, said heat seal adhesivedeposit being in the form of a band extending around the inner surfaceof the panels, and the deposit of heat seal adhesive being adapted toform a heat seal closure that forms a bond that is stronger than theweaker bond formed by the cold seal bond at the elevated temperaturesproduced by a microwave cooking operation.
 5. The roll of microwavecooking bags of claim 4, includinga susceptor mounted on one of thepanels.
 6. The roll of microwave cooking bags of claim 4, includingatacking deposit of heat seal adhesive on the gusseted panels at the heatseal end of the bag for tacking the gusseted panels together.
 7. Theroll of microwave cooking bags of claim 4, includingink printing on theouter surface of the bags.
 8. The roll of microwave cooking bags ofclaim 4,wherein the bags have a liner inside said side panels.
 9. Theroll of microwave cooking bags of claim 4,said weaker cold seal bondbeing adapted to provide controlled venting at a desired stage ofmicrowave cooking.
 10. A roll of microwave popcorn bags comprisingacontinuous tubular web having a plurality of successive popcorn bagsconnected together serially in end-to-end relationship and separated bycut-off lines, said bags being of pinch bottom bag constructionincluding a pair of opposed rectangular side panels joined by a pair ofopposed inwardly-folded gusseted side panels, said rectangular sidepanels having a middle portion and two side portions, said bags havingan open end and a closed end, said bags being made of grease-resistantpaper material, a cold adhesive sealing band across the inside of theclosed end of the bag which seals the gusseted side panels to the sideportions of said opposed rectangular side panels so that the sealedgusseted side panels form flaps, and which seals the middle portion ofsaid opposed rectangular side panels together, said bags having alongitudinal seam, said longitudinal seam being sealed by an aqueousadhesive, said cold adhesive being an adhesive which exhibits anaffinity for itself whereby when two separate surfaces having said coldadhesive thereon are brought together under pressure they exhibit astrong tendency to stick to each other which provides a fiber tearing ordestruct bond on the paper material without the aid of heat or dwelltime, as is required in a typical heat seal, when brought together underpressure only, said cold seal band providing a bond which at ambienttemperature cannot be opened without tearing the paper material, butwhich at elevated temperature, such as that produced by a microwavecooking operation, is softened to form a peelable closure bond that isopened easily without tearing the paper material by manually applying aseparating force which pulls the panels apart, a deposit of heat sealadhesive at the open end of the bags for use in closing this end of thebag after the bag is filled with popcorn kernels, said heat sealadhesive deposit being in the form of a band extending around the innersurface of the panels, the deposit of heat seal adhesive being adaptedto form a heat seal closure that forms a bond that is stronger than theweaker bond formed by the cold seal bond at the elevated temperaturesproduced by a microwave cooking operation, said weaker cold seal bondbeing adapted to provide controlled venting at a desired stage ofmicrowave cooking, a susceptor mounted on one of the panels, a tackingdeposit of heat seal adhesive on the gusseted panels at the heat sealend of the bag for tacking the gusseted panels together, ink printing onthe outer surface of the bags, and a liner inside said side panels ofthe bags.